GE CARESCAPE - CO₂ measurement practicalities; Ventilation management

CO2withCAPNOSTATMainstream,CapnoFlexLF,andDualCO2modules
1.Expiration
2.Cardiogenicoscillations
Cardiogenicoscillationsappearwhen:
●AcontinuousfreshgasowisfedintothepatientY-piece.
●SidestreamgassamplingisdoneattheY-piece.
●Thepatientisventilatedwithalongexpirationtimeorlowrespirationtimes,and
whenthereisalongzeroowatend-expirationforsomeotherreason.
Oscillationscanbeeliminatedbyaddingaspacerwitha5mldeadspacebetween
theY-pieceandtheairwayadapter.Increaseddeadspacecreatesabuffervolume
betweentheY-pieceandthesamplingpoint,preventingtheinspiratoryandexpiratory
airfrommixingduringgassampling.MisinterpretationofEtCO
2
informationcanbe
avoidedthroughidentifyingcardiogenicoscillationandunderstandingthereasons
forit.
CO₂measurementpracticalities
Ventilationmanagement
Normoventilation(adequatealveolarventilationofapatient)canbemaintained
bymonitoringtheend-tidalcarbondioxideandoxygenconcentrations,and
adequacyofventilationcanbemaintainedbymonitoringairwaypressures,volumes
andspirometryloops.Alveolarminuteventilationisusuallyadjustedtoachieve
normocapnia,whereEtCO
2
isintherangeof4.5%to5.5%(34mmHgto41mmHg).
Thisiscallednormoventilationasitisthenormalsituationinhealthypeople.
AlowEtCO
2
concentration(EtCO
2
<4%/30mmHg)indicateshyperventilation.
NOTE
AlowEtCO
2
valueinitselfisdependentfromtheventilation
volumevs.circulationstatus(lungperfusion).Thismeansthat
incaseoflowbloodpressure(e.g.shock)orshuntinglow
EtCO
2
valuesmaybeobservedwhileusinga“normal”TV/MV.
IncreasedEtCO
2
concentration(EtCO
2
>6.0%/45mmHg)indicateshypoventilationor
ineffectivealveolarventilation,whichwillleadtohypercapniaandrespiratoryacidosis.
IncreasedinspiratoryCO
2
(FiCO
2
)concentrationsmayalsobecausedby:
●ExhaustedCO
2
absorber.
●Malfunctionofthebreathingsystemvalves.
2062971-001CARESCAPEModularMonitors319